Let P(x) be the number of people in the U. S. who own a cell phone x years after 1990. Your friend says that P(x+1)>P(x) for any x because x+1 is always greater than x . Is your friend correct? Explain.

yes; The value of the function increases as x increases.

no; The value of the function decreases as x increases.

yes; The value of x increases by 1 as the value of the function increases by 1.

no; It is not known whether the value of the function will increase or decrease as increases.